The invention generally relates to a method for the electrical connection of angularly disposed surfaces, each comprising one or more electrically conductive pads. The invention further relates to an electronic assembly fabricated from the method. The invention provides a simple and cost-effective method for interconnecting such angularly disposed, electrically conductive surfaces as is required for instance, in the interconnection of a three-dimensional, multi-layer electronic module to a printed circuit board.
There is a continuing demand for higher circuit density in a wide variety of electronic applications such as consumer electronics, space hardware, and military weaponry and hardware. To avoid the two-dimensional limitations of conventional printed circuit boards, industry has begun using high density, three-dimensional, multilayer modules comprised of individual interconnected layers of microelectronic circuitry which occupy very little surface area but provide greatly increased circuit density per given area. The individual layers in the respective modules may comprise bare integrated circuit die, encapsulated integrated circuit die such as NEO-LAYERS, modified prepackaged parts, or stacked commercial off the shelf packaged parts such as ball grid array packages.
Examples of such three-dimensional modules include those disclosed in U.S. Pat. No. 4,403,238, U.S. Pat. No. 4,525,921, U.S. Pat. No. 4,672,737, U.S. Pat. No. 5,701,233, U.S. Pat. No. 6,072,234, U.S. Pat. No. 6,967,411, U.S. Pat. No. 7,174,627, all to common assignee, Irvine Sensors Corp., the assignee of the present application
Another example of using the “Z-axis” to increase circuit density is the use of a daughterboard/motherboard configuration where one or more printed circuit boards are mounted to a motherboard at an approximately perpendicular angle
Required input/output and power/ground interfaces between a multi-layer module or daughterboard and a printed circuit board are presently provided in different formats including ball grid array or wire bond interfaces. Each of these methods has a measure of inefficiency due to the difficulty, time and expense associated with the design and assembly of such interfaces as well as problems with signal path length and related parasitic inductance.
Providing conductive contact pads on a lateral surface of the multilayer module or daughterboard for interconnection with the printed circuit board is desirable due to ease of assembly, reworkability and shorter lead length. There are very few simple and efficient methods for the interconnection of electronic assemblies with interconnection conductive patterns that lie in a perpendicular plane to each other.
The instant invention provides a simple, cost-effective and reliable method for the electrical interconnection of perpendicular or angularly disposed conductive surfaces using industry standard wire bonding techniques and equipment.